One type of prior art ink-jet printer has a printhead mounted to a carriage that is moved back and forth over print media, such as paper. As the printhead passes over appropriate locations on the printing surface, a control system activates ink-jets on the printhead to eject ink drops onto the print media to form desired images and characters. To work properly, such printers must have a reliable supply of ink for the printhead.
One category of ink-jet printer uses a disposable ink pen that is mounted to and moves with the carriage. In some types of ink-jet printers in this category the ink reservoir portion of the ink pen is replaceable separate from the ink pen. In others, the entire printhead and ink reservoir are replaced as a unit once the ink is depleted.
Another category of printer uses reservoirs that are not located on the carriage. In this category of printer the reservoir intermittently replenishes the printhead with ink. The printhead travels to a stationary reservoir periodically for replenishment. Another type makes use of a replaceable ink reservoir connected to the printhead by a fluid conduit. The printhead is replenished with ink through this fluid conduit.
In the parent application to this application Ser. No. 08/785,580, a replaceable cartridge is described which has a memory device mounted to the housing. When inserted into the printer station, an electrical connection between the printer and the memory device is established. This electrical connection allows for the exchange of information between the printer and the memory. The memory device contains ink container parameters that are utilized by the printer to ensure reliable printer operation and print quality. These parameters are updated automatically when the cartridge is mounted to the printer. The exchange of information assures compatibility of the cartridge with the printer.
Another function for the memory device discussed in Ser. No. 08/785,580 is to prevent the use of the cartridge after the supply of ink is depleted. Operating a printer when the reservoir has been depleted of ink can damage or destroy the printhead portion of the cartridge. The memory devices concerned with this application are associated with the ink container and are updated with information relating to the current amount of ink remaining in the reservoir. When a new ink container is installed, the printer will read information from the memory device, which indicates the amount of ink remaining in the reservoir. During usage, the printer counts the drops of ink being used and updates the memory device associated with the ink container to indicate how much ink is remaining in the ink containers. When the ink is substantially depleted, this type of memory device will provide a signal to the printer which indicates that the reservoir is out of ink or low in ink. When substantially depleted of ink, these ink reservoirs are typically discarded and a new ink reservoir along with a new memory device is installed.